The instant invention relates to a novel expandable composition. The instant invention also relates to a method of using the composition, for example, as an automotive cavity sealant.
Expandable sealants are known in this art such as described in U.S. Pat. Nos. 4,427,481; 4,874,650; 5,266,133; 5,373,027; 5,506,025; 5,266,133; 5,373,027; and 5,678,826; and European Patent No. EP 0 730 998B1; the disclosure of each of which is hereby incorporated by reference. One conventional cavity sealing arrangement and method is described in U.S. Pat. No. 5,040,803; the disclosure of which is also hereby incorporated by reference. Other convention cavity sealants comprise polyvinyl chloride (PVC) based materials that are pumped into location and, in some cases, expand after being exposed to a sufficient amount of heat. Conventional sealants also include polyurethane based or containing foams. Typically, these sealants are employed in automotive applications for filing cavities, stiffening adjacent components and dampening sound/vibrations. Conventional sealant compositions may be limited in their application due to the temperature and time required to cause the sealant to expand. Certain conventional compositions also require the addition of heat to produce the expandable composition as well as to cause the composition to expand. There is a need in this art for an expandable composition that: 1) is activated at a relatively low temperature, 2) adheres to a metal substrate, 3) is easily installed and remains in a predetermined location and 4) for some applications is resistant to fuel, e.g., diesel and gasoline.
The instant invention solves problems associated with conventional sealants and methods by providing a novel composition that can be molded into a predetermined shape and expanded by being exposed to a sufficient amount of heat, e.g., an external source of heat. In contrast to conventional sealants, the inventive composition can: 1) have a predetermined shape, e.g., by injection molding, 2) located, e.g., within a cavity, or around or upon a member to be sealed, prior to/post assembly while remaining in a predetermined location, 3) employed in a wide range of applications, 4) produced at relatively low temperatures; 5) expanded at relatively low temperatures, e.g, after being installed within a cavity; and 6) recycled as scrap material post cure.
The inventive composition may be employed in automotive applications, e.g., the composition may be used in accordance with the guidelines set forth in Ford Specification No. ESB-M 18P11 A, WSB-M 18P11A2, General Motors Specification No. 9984188 C/D/G and DaimlerChrysler Specification No. MS-CD 627 B/E, 644, and 466; the disclosure of these Specifications is hereby incorporated by reference.
By tailoring the inventive composition, the expansion initiation temperature of the composition, degree of expansion, time until fully expanded, among other processing characteristics, can be predetermined to satisfy a wide range of end-uses. The inventive composition can expand about 450 to about 800 volume % at temperatures of about 250 to about 375 F. (adjacent metal temperature), depending upon the characteristics of the composition. When the heat of expansion is provided from a powder coat system, the temperature can be 385 F. to about 400 F. For example, the inventive composition can expand at least about 500% at a temperature of about 300 F. Depending upon the desired expansion rate and expansion initiation temperature, the inventive composition can be tailored to expand 800 to 1,000% and have expansion initiation temperatures from about 120 to 170 C. (adjacent metal temperature).